1. Field of the Invention
The present invention relates to rulers, and more particularly to a triangle ruler that can be used to draw a variety of different angles of lines.
2. Description of the Related Art
People may need to draw a variety of lines by hand to meet different drawing needs. When drawing a variety of different angles of lines, mapping tools such as ruler, triangle ruler and protractor may be used.
Linear mapping tools include a ruler marked with a linear scale and a carbon pencil. Subject to the guide of the ruler, the carbon pencil is driven to draw a line segment subject to a predetermined length and then to extend a known line segment.
However, the known technique is to draw a line segment of a predetermined length subject to the assistance of one straight edge of the ruler and the linear scale at the ruler. During mapping, one may need to draw vertical lines of predetermined lengths, parallel lines subject to predetermined pitches, and lines that define with the respective vertical lines and respective contained angle. Using one single ruler cannot draw the aforesaid different angles of lines. At this time, a triangle ruler, protractor or other mapping tools shall be needed. However, it is inconvenient to carry a large number of mapping tools and to use different mapping tools during drawing. Therefore, there is room for improvement on conventional mapping tools.